Evaluation and presentation of robustness of a treatment plan

Abstract

Systems and methods for evaluating and presenting robustness of a radiotherapy treatment plan for use in radiotherapy are discussed. An exemplary system includes a processor to generate, in a radiation simulation in accordance with the treatment plan under evaluation, dose distributions at an anatomical structure under a nominal condition and one or more artificially imposed uncertainty conditions, determine a dose distribution characteristic for the anatomical structure using the received dose distributions, and generate a robustness indicator of the treatment plan. The dose distributions may be determined at a target structure and one or more structures at risk, and presented graphically in a three-dimensional dose-volume-structure space. An output circuit can output the dose distribution characteristic or the robustness indicator to a user or a treatment planning system.

What is claimed is: 
     
       1. A system for evaluating robustness of a radiotherapy treatment plan used by a radiation therapy device to treat a patient, the system comprising:
 a processor configured to:
 generate, in a radiation simulation in accordance with the radiotherapy treatment plan, dose distributions at an anatomical structure under a nominal condition and one or more artificially imposed uncertainty conditions; 
 determine a dose distribution characteristic for the anatomical structure using the dose distributions; and 
 generate a robustness indicator of the radiotherapy treatment plan based on the dose distribution characteristic; and 
 
 a memory configured store the dose distribution characteristic or the robustness indicator accessible by a user or a treatment planning system. 
 
     
     
       2. The system of  claim 1 , wherein the anatomical structure includes a target structure to receive radiation treatment and at least one structure at risk to avoid radiation treatment, and wherein the processor is configured to:
 determine a first dose distribution characteristic using first dose distributions at the target structure, and a second dose distribution characteristic using second dose distributions at the at least one structure at risk; and 
 generate a three-dimensional (3D) graphical representation of the first and second dose distribution characteristics in a dose-volume-structure space to be displayed on a display. 
 
     
     
       3. The system of  claim 1 , wherein the dose distributions include dose-volume histograms (DVHs) each representing tissue volumes of the anatomical structure receiving respective radiation doses, the DVHs including:
 a nominal DVH corresponding to the nominal condition; and 
 one or more uncertainty DVHs corresponding to the one or more artificially imposed uncertainty conditions using the dose distributions. 
 
     
     
       4. The system of  claim 3 , wherein the dose distribution characteristic includes (1) a first boundary DVH corresponding to a lowest dose across a range of volumes of the anatomical structure and (2) a second boundary DVH corresponding to a highest dose across the range of volumes of the anatomical structure, the first and second boundary DVHs defining a DVH range; and
 wherein the processor circuit is configured to generate a DVH band graphically representing the DVH range to be displayed on a display. 
 
     
     
       5. The system of  claim 4 , wherein the processor is configured to generate the robustness indicator of the radiotherapy treatment plan based on at least one of:
 a first deviation of the first boundary DVH from the nominal DVH; 
 a second deviation of the second boundary DVH from the nominal DVH; or 
 a third deviation of the second boundary DVH from the first boundary DVH. 
 
     
     
       6. The system of  claim 3 , wherein the processor is configured to:
 determine the dose distribution characteristic including identifying, from the one or more uncertainty DVHs, an extreme-scenario DVH based on a dosimetric criterion including at least one of a reference tissue volume or a reference radiation dose; and 
 generate a graphical representation of the extreme-scenario DVH to be displayed on a display. 
 
     
     
       7. The system of  claim 6 , wherein the processor is configured to generate the robustness indicator of the radiotherapy treatment plan based on a deviation of the extreme-scenario DVH from the dosimetric criterion. 
     
     
       8. The system of  claim 6 , wherein the processor is configured to:
 generate, for a target structure to receive radiation treatment, a first set of DVHs including a first nominal DVH corresponding to the nominal condition and first one or more uncertainty DVHs corresponding to the one or more artificially imposed uncertainty conditions; and 
 identify, from the first set of DVHs, a first extreme-scenario DVH that has at least one of (1) a minimum radiation dose received by a first reference tissue volume of the target structure, or (2) a minimum tissue volume of the target structure receiving a first reference radiation dose. 
 
     
     
       9. The system of  claim 6 , wherein the processor is configured to:
 generate, for a structure at risk to avoid radiation treatment, a second set of DVHs including a second nominal DVH corresponding to the nominal condition and second one or more uncertainty DVHs corresponding to the one or more artificially imposed uncertainty conditions; and 
 identify, from the second uncertainty DVHs, a second extreme-scenario DVH that has at least one of (1) a maximum radiation dose received by a second reference tissue volume of the structure at risk, or (2) a maximum tissue volume of the structure at risk receiving a second reference radiation dose. 
 
     
     
       10. The system of  claim 3 , wherein the processor is configured to:
 determine the dose distribution characteristic including identifying, from the one or more uncertainty DVHs, one or more out-of-range DVHs falling outside a tolerance margin based on a dosimetric criterion including at least one of a reference tissue volume or a reference radiation dose; and 
 generate an out-of-range DVH sub-band graphically representing the identified one or more out-of-range DVHs to be displayed on a display. 
 
     
     
       11. The system of  claim 10 , wherein the processor is configured to generate the robustness indicator of the radiotherapy treatment plan using a count of the out-of-range DVHs relative to a count of the one or more uncertainty DVHs. 
     
     
       12. The system of  claim 10 , wherein the processor is configured to:
 generate, for a target structure to receive radiation treatment, a first set of DVHs including a first nominal DVH corresponding to the nominal condition and first one or more uncertainty DVHs corresponding to the one or more artificially imposed uncertainty conditions; and 
 identify, from the first uncertainty DVHs, one or more out-of-range DVHs each having a lower radiation dose at a reference tissue volume than a first reference radiation dose by a first tolerance margin. 
 
     
     
       13. The system of  claim 10 , wherein the processor is configured to:
 generate, for a structure at risk to avoid radiation treatment, a second set of DVHs including a second nominal DVH corresponding to the nominal condition and second one or more uncertainty DVHs corresponding to the one or more artificially imposed uncertainty conditions; and 
 identify, from the second uncertainty DVHs, one or more out-of-range DVHs each having a higher radiation dose at a reference tissue volume than a second reference radiation dose by a second tolerance margin. 
 
     
     
       14. The system of  claim 1 , wherein the radiotherapy includes a proton therapy, and wherein the dose distributions are determined for an anatomical structure under a nominal condition and one or more artificially imposed uncertainty conditions in a simulated proton therapy. 
     
     
       15. The system of  claim 14 , wherein the one or more artificially imposed uncertainty conditions include deviations from the nominal condition representing one or more of range uncertainties associated with a proton beam or patient setup errors. 
     
     
       16. The system of  claim 1 , wherein the processor is further configured to modify, or generate a recommendation to modify, the radiotherapy treatment plan based on the robustness indicator of the radiotherapy treatment plan. 
     
     
       17. A method for evaluating robustness of a radiotherapy treatment plan used by a radiation therapy device to treat a patient, the method comprising:
 generating, via a processor, dose distributions at an anatomical structure under a nominal condition and one or more artificially imposed uncertainty conditions using the radiotherapy treatment plan; 
 determining a dose distribution characteristic for the anatomical structure using the dose distributions; 
 generating a robustness indicator of the radiotherapy treatment plan based on the dose distribution characteristic; and 
 providing the dose distribution characteristic or the robustness indicator to a user or a treatment planning system. 
 
     
     
       18. The method of  claim 17 , wherein the anatomical structure includes a target structure to receive radiation treatment and at least one structure at risk to avoid radiation treatment, the method comprising:
 determining a first dose distribution characteristic using first dose distributions at the target structure, and a second dose distribution characteristic using second dose distributions at the at least one structure at risk; and 
 generating a three-dimensional (3D) graphical representation of the first and second dose distribution characteristics in a dose-volume-structure space. 
 
     
     
       19. The method of  claim 17 , wherein the dose distributions include dose-volume histograms (DVHs) each representing tissue volumes of the anatomical structure receiving respective radiation doses, the DVHs including:
 a nominal DVH corresponding to the nominal condition; and 
 one or more uncertainty DVHs corresponding to the one or more artificially imposed uncertainty conditions using the dose distributions. 
 
     
     
       20. The method of  claim 19 , wherein the dose distribution characteristic includes (1) a first boundary DVH corresponding to a lowest dose across a range of volumes of the anatomical structure and (2) a second boundary DVH corresponding to a highest dose across the range of volumes of the anatomical structure, wherein:
 generating the robustness indicator of the radiotherapy treatment plan is based on a DVH range defined by the first and second boundary DVHs; and 
 providing the dose distribution characteristic or the robustness indicator includes displaying a DVH band graphically representing the DVH range. 
 
     
     
       21. The method of  claim 19 , comprising:
 identifying, from the one or more uncertainty DVHs, an extreme-scenario DVH satisfying a dosimetric criterion with respect to the nominal DVH; and 
 generating the robustness indicator of the radiotherapy treatment plan based on a deviation of the extreme-scenario DVH from the nominal DVH; 
 wherein providing the dose distribution characteristic or the robustness indicator includes displaying a graphical representation of the extreme-scenario DVH. 
 
     
     
       22. The method of  claim 19 , comprising:
 identifying, from the one or more uncertainty DVHs, one or more out-of-range DVHs falling outside a tolerance margin with respect to the nominal DVH; and 
 generating the robustness indicator of the radiotherapy treatment plan based on a count of the out-of-range DVHs relative to a count of the one or more uncertainty DVHs; 
 wherein providing the dose distribution characteristic or the robustness indicator includes displaying an out-of-range DVH sub-band graphically representing the identified one or more out-of-range DVHs. 
 
     
     
       23. The method of  claim 17 , comprising modifying, or generating a recommendation to modify, the radiotherapy treatment plan based on the robustness indicator of the radiotherapy treatment plan. 
     
     
       24. The method of  claim 17 , wherein the radiotherapy includes a proton therapy, and wherein the one or more artificially imposed uncertainty conditions include deviations from the nominal condition representing one or more of range uncertainties associated with a proton beam or patient setup errors.